JPH11273870A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a contrast ratio and visibility by blacking the base parts of a layer-to-layer insulating layer formed around hole injection electrodes and/or element separating structural bodies. SOLUTION: Since an electron injection electrode 5 is normally formed from a metal, it will reflect external light entering from a board 1 side and thereby causes a contrast ratio and visibility to be degraded. Then, a part of non- luminous parts that does not contribute to light emission is blackened by blacking a layer-to-layer insulating layer 3 and/or the base parts of element separating structural bodies 7, and thereby, the reflected light from the non-luminous parts is restrained, so that the contrast ratio and the visibility are improved. As a means of blacking the base parts of the layer-to-layer insulating layer 3 and the like, they are formed from a black-colored or relatively, close to a black material. For this material, a material such as ferrous oxide, silicon, amorphous carbon or a composition prepared by adding carbon to polyimide resin is preferable. It is preferable that the quantity of carbon black added to organic resin be 10-50 mol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an information display panel,
The present invention relates to a structure of an organic EL device which is used for an electric component such as a home appliance, an automobile, a motorcycle, and the like, such as an instrument panel for an automobile, a display for displaying a moving image and a still image, and is configured using an organic compound.

[0002]

2. Description of the Related Art In recent years, organic EL devices have been actively studied,
It is being put to practical use. In this method, a hole transport material such as triphenyldiamine (TPD) is formed into a thin film on a transparent electrode (hole injection electrode) such as tin-doped indium oxide (ITO) by vapor deposition, and then an aluminum quinolinol complex (A
1q3) as a light emitting layer, and a metal electrode such as Mg having a small work function (electron injection electrode)
This element has a basic structure and has a very high luminance of several hundreds to several tens of thousands cd / m ² at a voltage of about 10 V, and thus has attracted attention as a display for home electric appliances, automobiles, motorcycle electric components and the like.

When constructing a display or the like using such an organic EL element, one of the major issues is to improve the image quality. As factors that affect the image quality, there are indirect contents such as contrast and visibility in addition to those directly related to the light emission function, such as light emission luminance and light emission wavelength. Various attempts have been made to improve contrast and legibility, and various measures have been taken such as providing an anti-glare filter and providing a black filter layer called a black matrix. However, there is a strong demand for improving the contrast and visibility even in displays using such anti-glare filters, black matrices, and the like, and further improvements in elements have been desired.

In addition, if the element alone has a certain level of contrast ratio and visibility, it can be used as it is without using an antiglare filter, a black matrix, or the like, depending on the purpose of use, thereby reducing costs. Can be.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic EL device having improved contrast ratio and visibility. Organic EL that can realize low cost
It is to provide an element.

[0006]

The above object is achieved by the following constitution. (1) A hole injection electrode, an electron injection electrode, and one or more organic layers between these electrodes, and an interlayer insulating layer and / or an element isolation structure formed around the hole injection electrode. An organic EL device having a black base. (2) The organic EL device according to (1), wherein the interlayer insulating layer and / or the base of the element isolation structure contains ferrous oxide, silicon, or amorphous carbon. (3) The base according to (1), wherein the interlayer insulating layer and / or the base of the element isolation structure has polyimide and carbon.
Organic EL device.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The organic EL device of the present invention has a hole injection electrode, an electron injection electrode, and one or more organic layers between these electrodes, and is formed around the hole injection electrode. The base of the inter-layer insulating layer and / or the element isolation structure is black. As described above, by setting the base of the interlayer insulating layer and / or the element isolation structure to black, the non-light emitting region visible from the outside is set to black, so that the contrast ratio is improved or the visibility is improved.

Preferably, the base of the interlayer insulating layer and / or the element isolation structure contains FeO or Si, or polyimide and amorphous carbon. With these materials, black can be obtained.

As shown in FIG. 1, for example, the organic EL element has a hole injection electrode 2 of ITO or the like on a substrate 1 and an interlayer insulating layer 3 around the electrode 1 as shown in FIG. Furthermore, an element isolation structure 7 is provided on the interlayer insulating layer 3 and around the hole injection electrode 2. An organic layer 4 and an electron injection electrode 5 are further laminated on the hole injection electrode 2 in a region partitioned by the element isolation structure 7, thereby forming an organic EL element. The element isolation structure 7 has a base 7b and an overhang portion 7a formed on the base 7b, and the organic layer 4 and the electron injection electrode stacked on the hole injection electrode 2 by the overhang portion 7a. The layer 5 is regulated, and a specific region in the device is divided or separated as a whole.

In addition, the organic EL element may be formed, if necessary, in addition to the structure described above, for example, a protective electrode for a hole injection electrode, a wiring electrode for an electron injection electrode, an auxiliary electrode, and the like. Therefore, these are omitted in the above illustrated example. The organic layer includes at least one organic layer having a function necessary for light emission, such as a hole injection transport layer, a light emitting layer, and an electron injection transport layer.

[0011] The electron injection electrode is usually a metal. For this reason, external light that enters from the substrate side via the hole injection electrode, the interlayer insulating layer, the organic layer, and the like is reflected, which causes a reduction in contrast ratio and visibility. Therefore, by making the base of the interlayer insulating layer and / or the element isolation structure black, at least a part of the region that does not contribute to light emission, that is, a part of the non-light-emitting part is blackened, and reflected light from the non-light-emitting part And improve the contrast ratio and visibility. Further, the blackening of the non-light-emitting portion also has the effect of directly improving visibility and improving image quality.

As means for making the base of the interlayer insulating layer and / or the element isolation structure black, a black or relatively black material may be used, or a black or relatively black material may be added. What is necessary is just to form with the material which carried out. These materials need not be completely black, but may be dark enough to attenuate incident light or reflected light. Either the interlayer insulating layer or the element isolation structure may be black, or both may be black. As black, a wavelength of 400 with respect to white light
Preferably, it has a reflectance of not more than 50%, more preferably not more than 40% at a wavelength of from 700 nm to 700 nm.

As such a material, ferrous oxide (Fe)
O), silicon (Si), amorphous carbon or an organic resin such as a polyimide resin or an acrylic resin, particularly, a resin obtained by adding carbon, that is, carbon black to a polyimide resin. Oxidation 1
It is generally difficult for iron to exist in the stoichiometric composition of FeO, and when Fe _x O is used, x = 0.
It is about 0.95. These materials can be used for both the interlayer insulating layer and the base of the element isolation structure. .

[0014] The amount of carbon black added to the organic resin is preferably 10 to 50 mol%, more preferably 3 to 50 mol%.
0 to 40 mol%. The primary particle size of the carbon black is usually about 1 to 500 nm, particularly 10 to 100 nm.
It is about.

Ferrous oxide (FeO), silicon (S
i) In the case where the base of the interlayer insulating layer and / or the element isolation structure is formed of amorphous carbon, it is preferable to use a sputtering method. Each of these layers can be formed in a predetermined pattern by using a mask, photolithography, or the like.

When only the interlayer insulating layer is black and the element isolation structure is used as it is, the material constituting the element isolation structure is not particularly limited, and the material for forming the element isolation structure may be formed on the hole injection electrode or on the interlayer insulation layer. Since the organic layer, the electron injection electrode, and the like are further laminated thereon, it is a material that does not interfere with these structural films and is not electrically connected to each of the separated elements. Is preferred.
Further, the base portion and the overhang portion may be formed using the same material or different materials. However, it is preferable to use different materials because an overhang shape is easily obtained.

The interlayer insulating layer is not limited to the above materials unless it is blackened. The interlayer insulating layer is formed by sputtering or vacuum depositing an inorganic material such as silicon oxide such as SiO ₂ , silicon nitride, or FeO. Any material may be used as long as it has an insulating property, such as a silicon oxide layer formed by SOG (spin-on-glass), a coating of a resin material such as a photoresist, a polyimide, or an acrylic resin. However, since there is a hole injection electrode such as ITO (electron injection electrode in a so-called reverse lamination) below the insulating layer, a material that can be patterned so as not to damage the electrode when patterning into an insulating layer shape. It is preferable to use Examples of such a preferable interlayer insulating layer material include, for example, polyimide.

The thickness of the interlayer insulating layer is preferably about 50 to 750 nm. If the thickness of the interlayer insulating layer is too small, it is difficult to obtain the effects of the present invention. If the thickness is too large, the organic layer, the electron injecting electrode, the auxiliary electrode, and the like may be stepped (the film formed at or after the step, particularly at the portion from the edge of the interlayer insulating layer to the center of the light emitting portion). Discontinuities) may occur. The formation region of the interlayer insulating layer is usually formed around the hole injection electrode. The necessary film formation area of the interlayer insulating layer is determined by the size of the light-emitting area, the light-emitting pattern, and the like, and is not particularly limited. In general, the width is 5 to 50 μm on the electrode and 5 to 50 μm on the substrate. Is formed in a width of

When the interlayer insulating layer is formed by a sputtering method,
Although not particularly limited, RF sputtering and DC sputtering are preferable. The input power is preferably in a range of 0.1 to 10 W / cm ² , particularly 0.5 to 7 W / cm ^{2 in} a DC sputtering apparatus. Further, the film formation rate is preferably in the range of 5 to 100 nm / min, particularly 10 to 50 nm / min. The RF sputtering is not particularly limited as long as it has a power supply capable of supplying a high frequency in an RF band. However, the frequency is usually 13.56 MHz and the input power is about 100 to 500 W.

The sputtering gas is not particularly limited, and an inert gas such as Ar, He, Ne, Kr, and Xe, or a mixed gas thereof may be used. The sputtering gas pressure is preferably 0.3 to 3 for RF sputtering.
0 Pa, more preferably about 0.5 to 1.0 Pa. Further, it is about 0.1 to 20 Pa by DC sputtering.

When a resin-based material such as photoresist, polyimide, or acrylic resin is used, it can be provided by ordinary coating, spin coating, dipping, or the like.

In the lithography step of forming an interlayer insulating layer in a predetermined pattern, usually, a resist is applied to a substrate on which an inorganic material as described above is formed or a substrate to which a solution of an organic polymer is applied, An electron beam, ultraviolet light,
After exposure to X-rays or the like, development is performed with an appropriate alkaline solution. Next, the interlayer insulating layer is etched, and then the resist is removed. The thickness of the resist film is usually about 1 to 2 μm.

That is, the above resist film is exposed to a predetermined pattern. An electron beam, an ultraviolet ray, an X-ray, or the like is used for the exposure, and irradiation may be performed according to a usual method. In addition, a predetermined method may be appropriately selected for drawing, such as using a mask, depending on an electron beam, ultraviolet light, or the like to be used. Thereafter, prebaking is performed, and development is performed using an alkaline solution.

When the resist has a negative shape, the resist film in the unexposed portion is dissolved and removed, and the substrate and the base in that portion are exposed. Thereafter, post baking is performed.

After the development, the substrate is etched using the resist film remaining on the substrate as a protective film. The etching may be wet etching using a chemical etching solution or dry etching using plasma or accelerating ions. The chemical etching solution used for the wet etching may be appropriately selected according to the material of the substrate, and H ₂ O: HF: CH ₃ COOH = 5:
In addition to 1:10, an HF solution, a mixed solution of NH ₄ F / HF / H ₂ O, and the like can be given.

Further, the plasma gas used in the plasma etching, which is widely used as a dry etching may be appropriately selected depending on the material of the adherend, SF _6, CHB
r ₃ , CF _{4 and the} like.

The specific method and conditions of the etching may be in accordance with a conventional method. After completion of the etching, the resist film is removed.

Materials used for forming the base of the element isolation structure include organic resin films such as polyimide resin and acrylic resin, SiO ₂ , SiN _x , a-Si, and SOG (Spin).
onGlass), a metal thin film such as Al, which can be easily thickened and has a small stress, and the like. Preferably, a polyimide resin, SiO ₂ , SOG,
Al or the like. As a material used for forming the overhang portion, a material having photosensitivity is preferable, for example, a photoresist, a photosensitive polyimide, or SiO 2.
_{2, SiN x, Al 2 O} 3, CrO X, a-Si, Si
Hard insulating film such as C or semiconductor film, or Cr, Ta, M
A conductive thin film such as o, Ni, W, Ti, TiN, ZnO, and ITO can be used, and an insulating film, a semiconductor film, and a film obtained by laminating a photosensitive film on a conductive thin film can be used. , Preferably, photoresist, SiO ₂ , Cr, T
i.

Although the size of the base is not particularly limited, it usually functions sufficiently as long as it has a width of 1 μm or more, but it is particularly preferably 5 μm or more, and the height (film thickness) is 0 μm. .2 μm or more, especially about 0.5 to 10 μm. Further, the size of the overhang portion is not particularly limited, but it is preferable that the overhang portion has a structure having an overhang length that is at least about half of the film thickness of the base portion. Height (film thickness) 0.1-1
0 μm, particularly preferably about 0.2 to 5 μm. The combined height is 1-20 μm, especially 0.7-10 μm
The degree is preferred.

In order to form an element isolation structure, first, a base layer made of the above-mentioned base material is formed on a substrate on which a hole injection electrode, an interlayer insulating layer and the like are formed, preferably by using a resin film or an S film.
The OG film is formed by a spin coating method or a roll coating method, the insulating film or the semiconductor film is formed by a sputtering method or a CVD method, the metal film is formed by a vapor deposition method, and the like. A hang portion layer is formed. At the same time as exposing, developing and patterning this overhanging layer,
Alternatively, thereafter, the base layer may be etched, and the base layer may be over-etched so as to be smaller than the overhang portion layer to form an overhang body.
When a sputtering method is used to form the base, the conditions and the like are the same as those of the above-mentioned interlayer insulating layer. The method of forming the base portion and the overhang portion with a resin or the like may be in accordance with the photoresist method described for the interlayer insulating layer or the like.

The organic EL device of the present invention can be applied to displays using various organic EL devices, such as a matrix type display and a segment type display.

Next, the organic EL structure constituting the organic EL device of the present invention will be described.

Since the hole injection electrode is generally configured to extract light emitted from the substrate side, a transparent or translucent electrode is preferable. Examples of the transparent electrode include ITO (tin-doped indium oxide), IZO (zinc-doped indium oxide), ZnO, SnO ₂ , In ₂ O _{3, and the} like.
ZO (zinc-doped indium oxide) is preferred. ITO
Usually contains In ₂ O ₃ and SnO in a stoichiometric composition, but the O amount may be slightly deviated from this.

The thickness of the hole injecting electrode may be a certain thickness or more for sufficiently injecting holes.
The range is preferably from 0 to 500 nm, more preferably from 50 to 300 nm. The upper limit is not particularly limited, but if the thickness is too large, there is a fear of peeling or the like. If the thickness is too small, there is a problem in the film strength at the time of manufacturing, the hole transport ability, and the resistance value.

This hole injection electrode layer can be formed by a vapor deposition method or the like, but is preferably formed by a sputtering method.

As the electron injection electrode, a substance having a low work function is preferable. For example, K, Li, Na, Mg, La, C
e, Ca, Sr, Ba, Al, Ag, In, Sn, Z
It is preferable to use a single metal element such as n or Zr, or a two-component or three-component alloy system containing them for improving the stability. As an alloy system, for example, Ag · Mg (A
g: 1 to 20 at%), Al.Li (Li: 0.3 to 14)
at%), In.Mg (Mg: 50-80at%), Al.
Ca (Ca: 5 to 20 at%) and the like are preferable. Note that the electron injection electrode can be formed by an evaporation method or a sputtering method.

The thickness of the electron injecting electrode thin film may be a certain thickness or more capable of sufficiently injecting electrons.
Preferably, the thickness may be 1 nm or more. The upper limit is not particularly limited, but the thickness may be generally about 1 to 500 nm. A protective electrode may be further provided on the electron injection electrode.

The thickness of the protective electrode may be a certain thickness or more, preferably 50 nm or more, more preferably 100 nm or more, in order to secure electron injection efficiency and to prevent entry of moisture, oxygen or an organic solvent. The range of 100 to 1000 nm is preferred. If the protective electrode layer is too thin, the effect cannot be obtained, and the step coverage of the protective electrode layer is reduced, and the connection with the terminal electrode is not sufficient. on the other hand,
If the protective electrode layer is too thick, the stress of the protective electrode layer increases, so that the growth rate of dark spots increases.

The total thickness of the electron injecting electrode and the protective electrode is not particularly limited, but is usually 100 to 100.
It may be about 0 nm.

After forming the electrode, in addition to the protective electrode, S
inorganic materials iO _X such as Teflon, a protective film may be formed using an organic material such as fluorocarbon polymers containing chlorine. The protective film may be transparent or opaque, and the thickness of the protective film is about 50 to 1200 nm. The protective film may be formed by a general sputtering method, an evaporation method, a PECVD method, or the like, in addition to the reactive sputtering method.

Further, in order to prevent oxidation of the organic layer and the electrodes of the device, it is preferable to form a sealing layer on the device. The sealing layer adheres and seals the sealing plate using an adhesive resin layer in order to prevent moisture from entering. The sealing gas is Ar, H
e, an inert gas such as N _{2 and the} like are preferable. Further, the moisture content of the sealing gas is preferably 100 ppm or less, more preferably 10 ppm or less, and particularly preferably 1 ppm or less. Although there is no particular lower limit for the water content, it is usually about 0.1 ppm.

The material of the sealing plate is preferably a flat plate, and may be a transparent or translucent material such as glass, quartz, resin, etc., and glass is particularly preferred. As such a glass material, an alkali glass is preferable, and in addition, a glass composition such as soda-lime glass, lead-alkali glass, borosilicate glass, aluminosilicate glass, and silica glass is also preferable. As the plate making method, a roll-out method, a download method, a fusion method, a float method, or the like is preferable. As a surface treatment method for the glass material, a polishing treatment, a SiO ₂ barrier coat treatment, or the like is preferable. Among them, soda-lime glass produced by a float method and having no surface treatment can be used at a low cost, and is preferable. As the sealing plate, other than a glass plate, a metal plate, a plastic plate, or the like can be used.

The height of the sealing plate may be adjusted by using a spacer, and may be maintained at a desired height. Examples of the material of the spacer include resin beads, silica beads, glass beads, and glass fibers, and glass beads are particularly preferable. The spacer is usually a granular material having a uniform particle size, but the shape is not particularly limited, and may be various shapes as long as it does not hinder the function as the spacer. As the size, the diameter in terms of a circle is 1 to 20 μm, more preferably 1 to 10 μm, and especially 2 to 20 μm.
8 μm is preferred. Those having such a diameter have a grain length of 10
It is preferably about 0 μm or less, and the lower limit is not particularly limited, but is usually about 1 μm.

When a recess is formed in the sealing plate,
Spacers may or may not be used. The preferred size when used is within the above range,
Particularly, the range of 2 to 8 μm is preferable.

The spacer may be previously mixed into the sealing adhesive or may be mixed during bonding. The content of the spacer in the sealing adhesive is preferably 0.01
-30 wt%, more preferably 0.1-5 wt%.

The adhesive is not particularly limited as long as it can maintain stable adhesive strength and has good airtightness, but it is preferable to use a cationic curing type ultraviolet curing epoxy resin adhesive. .

The substrate material is not particularly limited, and can be appropriately determined depending on the material of the electrodes of the organic EL structure to be laminated. For example, a metal material such as Al or a transparent or transparent material such as glass, quartz or resin is used. The material may be translucent or opaque. In this case, in addition to glass, ceramics such as alumina, metal sheets such as stainless steel are subjected to insulation treatment such as surface oxidation, and thermosetting resins such as phenolic resin And a thermoplastic resin such as polycarbonate.

Next, the organic layer provided in the organic EL device will be described. The light emitting layer has a function of injecting holes (holes) and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. In the light emitting layer,
It is preferable to use a relatively electronically neutral compound.

The hole injection transport layer has a function of facilitating the injection of holes from the hole injection electrode, a function of stably transporting holes, and a function of preventing electrons.
The electron injection / transport layer has a function of facilitating the injection of electrons from the negative electrode, a function of stably transporting electrons, and a function of preventing holes. These layers increase and confine holes and electrons injected into the light emitting layer, optimize the recombination region, and improve luminous efficiency.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and vary depending on the forming method.
It is preferable that the thickness be in the range of 10 to 300 nm.

The thickness of the hole injecting and transporting layer and the thickness of the electron injecting and transporting layer depend on the design of the recombination / light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times. When the hole or electron injection layer and the transport layer are separated from each other, it is preferable that the injection layer has a thickness of 1 nm or more and the transport layer has a thickness of 1 nm or more. At this time, the upper limit of the thickness of the injection layer and the transport layer is usually about 500 nm for the injection layer and 500 nm for the transport layer.
It is about. Such a film thickness is the same when two injection / transport layers are provided.

The light emitting layer of the organic EL element contains a fluorescent substance which is a compound having a light emitting function. Examples of such a fluorescent substance include, for example, JP-A-63-26469.
No. 2 discloses at least one compound selected from compounds such as quinacridone, rubrene, and styryl dyes. Also, Tris (8
-Quinolinolato) quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof as a ligand such as aluminum, tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives. Further, phenylanthracene derivatives disclosed in Japanese Patent Application No. 6-110569, and Japanese Patent Application No. 6-11445.
No. 6 tetraarylethene derivative or the like can be used.

Further, it is preferable to use it in combination with a host substance capable of emitting light by itself, and it is preferable to use it as a dopant. In such a case, the content of the compound in the light emitting layer is 0.01 to 10% by weight, and more preferably 0.1 to 10% by weight.
It is preferably 1 to 5% by weight. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

As the host substance, a quinolinolato complex is preferred, and an aluminum complex having 8-quinolinol or a derivative thereof as a ligand is preferred. Such an aluminum complex is disclosed in JP-A-63-26469.
No. 2, JP-A-3-255190, JP-A-5-7073
3, JP-A-5-258859, JP-A-6-2158
No. 74 and the like.

Specifically, first, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis (benzo {f} -8-quinolinolato) zinc, bis (2-methyl-8-quinolinolato) aluminum Oxide, tris (8-quinolinolato) indium,
Tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro-
8-quinolinolato) gallium, bis (5-chloro-8-
Quinolinolato) calcium, 5,7-dichloro-8-quinolinolatoaluminum, tris (5,7-dibromo-
8-hydroxyquinolinolato) aluminum and poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane].

Further, in addition to 8-quinolinol or its derivative, an aluminum complex having another ligand may be used, such as bis (2-methyl-
8-quinolinolato) (phenolato) aluminum (III)
, Bis (2-methyl-8-quinolinolato) (ortho-
Cresolato) aluminum (III), bis (2-methyl-
8-quinolinolato) (meth-cresolate) aluminum
(III), bis (2-methyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-phenylphenolate)
Aluminum (III), bis (2-methyl-8-quinolinolato) (meth-phenylphenolato) aluminum (II
I), bis (2-methyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2-
Methyl-8-quinolinolato) (2,3-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-dimethylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(3,4-dimethylphenolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III) ), Bis (2-methyl-8)
-Quinolinolato) (2,6-diphenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,4,6-triphenylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(2,3,6-trimethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (2,
3,5,6-tetramethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (1-naphthrat) aluminum (III), bis (2-methyl-8
-Quinolinolato) (2-naphthrat) aluminum (II
I), bis (2,4-dimethyl-8-quinolinolato)
(Ortho-phenylphenolato) aluminum (III),
Bis (2,4-dimethyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2,
4-dimethyl-8-quinolinolato) (meta-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2 4-dimethyl-8
-Quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl) -4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III),
Bis (2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphthrat) aluminum (III);

In addition, bis (2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-
Methyl-8-quinolinolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis (2,4-dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-
2-methyl-8-quinolinolato) aluminum (III)-
μ-oxo-bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4
-Methoxyquinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-4-methoxyquinolinolato)
Aluminum (III), bis (5-cyano-2-methyl-
8-quinolinolato) aluminum (III) -μ-oxo-
Bis (5-cyano-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) -μ
-Oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) and the like.

Other host materials include Japanese Patent Application No.
Also preferred are phenylanthracene derivatives described in -110569 and tetraarylethene derivatives described in Japanese Patent Application No. 6-114456.

The light emitting layer may also serve as an electron injection / transport layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. These fluorescent substances may be deposited.

The light emitting layer is preferably a mixed layer of at least one kind of hole injecting and transporting compound and at least one kind of electron injecting and transporting compound, if necessary.
Further, it is preferable that a dopant is contained in the mixed layer. The content of the compound in such a mixed layer is preferably 0.01 to 20% by weight, more preferably 0.1 to 15% by weight.

In the mixed layer, a hopping conduction path of carriers is formed, so that each carrier moves in a polarly advantageous substance, and carrier injection of the opposite polarity is less likely to occur, so that the organic compound is less likely to be damaged. This has the advantage that the element life is extended. Further, by including the above-described dopant in such a mixed layer, the emission wavelength characteristics of the mixed layer itself can be changed, the emission wavelength can be shifted to a longer wavelength, and the emission intensity is increased, The stability of the device can be improved.

The hole injecting and transporting compound and the electron injecting and transporting compound used in the mixed layer may be selected from the compounds for the hole injecting and transporting layer and the compounds for the electron injecting and transporting layer described below, respectively. Among them, compounds for the hole injection transport layer include amine derivatives having strong fluorescence,
For example, it is preferable to use a triphenyldiamine derivative which is a hole transport material, a styrylamine derivative, or an amine derivative having an aromatic condensed ring.

As the compound capable of injecting and transporting electrons, it is preferable to use a quinoline derivative, furthermore a metal complex having 8-quinolinol or its derivative as a ligand, particularly tris (8-quinolinolato) aluminum (Alq3). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylethene derivatives.

As the compound for the hole injecting and transporting layer, an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative which is the above-described hole transporting material, a styrylamine derivative, or an amine derivative having an aromatic condensed ring is used. Is preferred.

The mixing ratio in this case depends on the respective carrier mobilities and carrier concentrations. In general, the weight ratio of the compound of the hole injection / transport compound / the compound having the electron injection / transport function is from 1/99 to less. 99/1, more preferably 10/90 to 90/10, particularly preferably 20/80
It is preferable to set it to about 80/20.

The thickness of the mixed layer is preferably not less than the thickness corresponding to one molecular layer and less than the thickness of the organic compound layer. Specifically, the thickness is preferably 1 to 85 nm, more preferably 5 to 60 nm, particularly preferably 5 to 50 nm.

As a method for forming the mixed layer, co-evaporation in which evaporation is performed from different evaporation sources is preferable. However, when the vapor pressures (evaporation temperatures) are about the same or very close, they are mixed in advance in the same evaporation board. Alternatively, it can be deposited. In the mixed layer, it is preferable that the compounds are uniformly mixed, but in some cases, the compounds may exist in an island shape. The light-emitting layer is generally formed to a predetermined thickness by vapor-depositing an organic fluorescent substance or by dispersing and coating the resin in a resin binder.

The hole injecting and transporting layer is described in, for example, JP-A-63-295695 and JP-A-2-19169.
4, JP-A-3-792, JP-A-5-234
681, JP-A-5-239455, JP-A-5-299174, JP-A-7-126225, JP-A-7-126226, JP-A-8-100
Various organic compounds described in JP-A-172, EP0650955A1, and the like can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TPD), an aromatic tertiary amine, a hydrazone derivative, a carbazole derivative, a triazole derivative, an imidazole derivative, an oxadiazole derivative having an amino group, polythiophene, etc. . These compounds may be used alone or in combination of two or more. When two or more kinds are used in combination, they may be stacked as separate layers or mixed.

When the hole injecting and transporting layer is provided separately for the hole injecting and transporting layer, a preferable combination can be selected from the compounds for the hole injecting and transporting layer. At this time, it is preferable to laminate the compounds in order from the hole injecting electrode (ITO or the like) with the smallest ionization potential. Further, it is preferable to use a compound having good thin film property on the surface of the positive electrode. Such a stacking order is the same when two or more hole injection transport layers are provided. With such a stacking order, the driving voltage is reduced, and the occurrence of current leakage and the occurrence and growth of dark spots can be prevented. In addition, when making the device,
Since thin film of about 1 to 10 nm can be made uniform and pinhole-free because of the use of vapor deposition, even if a compound having a small ionization potential in the hole injection layer and having absorption in the visible region is used, light emission can be achieved. It is possible to prevent a decrease in efficiency due to a color tone change or re-absorption. The hole injecting and transporting layer can be formed by vapor deposition of the above compound in the same manner as the light emitting layer and the like.

A quinoline derivative such as an organometallic complex having 8-quinolinol such as tris (8-quinolinolato) aluminum (Alq3) or a derivative thereof as a ligand is provided in the electron injection / transport layer provided as needed. An oxadiazole derivative, a perylene derivative, a pyridine derivative, a pyrimidine derivative, a quinoxaline derivative, a diphenylquinone derivative, a nitro-substituted fluorene derivative, or the like can be used. The electron injection / transport layer may also serve as the light emitting layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. The electron injecting and transporting layer may be formed by vapor deposition or the like, similarly to the light emitting layer.

In the case where the electron injecting and transporting layer is divided into an electron injecting layer and an electron transporting layer, a preferable combination can be selected from the compounds for the electron injecting and transporting layer. At this time, it is preferable to stack the compounds in descending order of the electron affinity value from the electron injection electrode side. Such a stacking order is the same when two or more electron injection / transport layers are provided.

The emission color may be controlled by using a color filter film, a color conversion film containing a fluorescent substance, or a dielectric reflection film on the substrate.

As the color filter film, a color filter used in a liquid crystal display or the like may be used.
The characteristics of the color filter may be adjusted in accordance with the light emitted from the organic EL element to optimize the extraction efficiency and the color purity.

When a color filter capable of cutting off short-wavelength external light that is absorbed by the EL element material or the fluorescent conversion layer is used, the light resistance of the element and the contrast of display are improved.

An optical thin film such as a dielectric multilayer film may be used instead of the color filter.

The fluorescent conversion filter film absorbs EL light and emits light from the phosphor in the fluorescent conversion film to convert the color of the emitted light. It is formed from a fluorescent material and a light absorbing material.

As the fluorescent material, basically, a material having a high fluorescence quantum yield may be used, and it is desirable that the fluorescent material has strong absorption in the EL emission wavelength region. In practice, laser dyes and the like are suitable, and rhodamine compounds, perylene compounds, cyanine compounds, phthalocyanine compounds (including subphthalocyanines, etc.) naphthalimide compounds, condensed ring hydrocarbon compounds, condensed heterocyclic compounds A styryl compound, a coumarin compound or the like may be used.

As the binder, a material that does not quench the fluorescence may be basically selected, and a binder that can be finely patterned by photolithography, printing, or the like is preferable. Further, a material that does not suffer damage during the formation of ITO or IZO is preferable.

The light absorbing material is used when the light absorption of the fluorescent material is insufficient, but may be omitted when unnecessary. As the light absorbing material, a material that does not quench the fluorescence of the fluorescent material may be selected.

For forming the hole injection transport layer, the light emitting layer and the electron injection transport layer, a uniform thin film can be formed.
It is preferable to use a vacuum deposition method. When vacuum deposition is used, the amorphous state or the crystal grain size is 0.1 μm
The following homogeneous thin film is obtained. If the crystal grain size exceeds 0.1 μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the charge injection efficiency is significantly reduced.

The conditions for vacuum deposition are not particularly limited.
The degree of vacuum is 0 ^-4 Pa or less, and the deposition rate is 0.01 to 1 nm /
It is preferable to set it to about sec. Further, it is preferable to form each layer continuously in a vacuum. If they are formed continuously in a vacuum, impurities can be prevented from adsorbing at the interface between the layers, so that high characteristics can be obtained. Further, the driving voltage of the element can be reduced, and the occurrence and growth of dark spots can be suppressed.

In the case where a plurality of compounds are contained in one layer when a vacuum evaporation method is used for forming each of these layers, it is preferable to co-deposit each boat containing the compounds by individually controlling the temperature.

The organic EL element is driven by a direct current or a pulse, and the applied voltage is usually about 2 to 20 V.

[0084]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. Example 1 A glass substrate was placed in a DC sputtering apparatus, and a tin-doped indium oxide sintered body (SnO: 10 wt.
%) As a target, and an ITO electrode was formed to a thickness of 100 nm. At this time, the film forming conditions were as follows: input power: 100 W, pressure during sputtering: 0.5 Pa, and sputtering gas: Ar + 1% O ₂ .

The substrate on which the hole injection electrode made of ITO was formed was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, pulled out from boiling ethanol and dried. Next, after cleaning the surface with UV / O ₃ , an interlayer insulating film was formed on the entire surface of the substrate. As the interlayer insulating layer, a material obtained by adding carbon black to polyimide was used. For polyimide, select a non-photosensitive material and make NMP (N-me
thyl pyrrolidone), add 30 mol% of carbon black (primary particle size: 50 nm) to this, and mix well.
The mixture was applied by a spin coating method,
Baking was performed for 0 minute and at 300 ° C. for 1 hour. The film thickness at this time was 200 nm.

Next, by photolithography,
A pattern having an opening for exposing a hole injection electrode serving as an actual light emitting portion was formed. After etching the interlayer insulating film with oxygen plasma, the resist was stripped.

Next, in order to form the base of the element isolation structure, polyimide is applied to a thickness of 2 μm on the substrate on which the ITO transparent electrode and the interlayer insulating layer have been formed, and then a positive electrode serving as an overhang portion is formed. A resist layer was applied to a thickness of 3 μm, exposed, and developed to obtain an element isolation structure.

Next, an organic layer, an electron injection electrode, and a wiring electrode were continuously formed. The vacuum was not broken until the formation of the protective electrode (wiring electrode) was completed.

Next, after the surface was washed with UV / O _3, it was fixed on a substrate holder of a vacuum evaporation apparatus, and the inside of the tank was 1 × 10 3.
^The pressure was reduced to ^-4 Pa or less. 4,4 ', 4 "-tris (-N
-(3-Methylphenyl) -N-phenylamino) triphenylamine (hereinafter, m-MTDATA) was deposited at a deposition rate of 0.2 nm / sec. To a thickness of 40 nm to form a hole injection layer. N, N'-diphenyl-N, N'-m-tolyl-4,4'-diamino-
1,1′-biphenyl (hereinafter referred to as TPD) is deposited at a deposition rate of 0.1%.
It was deposited at a thickness of 35 nm at 2 nm / sec to form a hole transport layer. Further, while maintaining the reduced pressure, tris (8-quinolinolato) aluminum (hereinafter, Alq3) was evaporated at a deposition rate of 0.5.
Vapor deposition at a thickness of 50 nm at 2 nm / sec.
It was a light emitting layer.

Then, while maintaining the reduced pressure, the EL element structure substrate was transferred from the vacuum evaporation apparatus to the sputtering apparatus, and the AlLi electron injection electrode (Li concentration: 6 at%) was formed to a thickness of 50 nm at a sputtering pressure of 1.0 Pa. A film was formed. At that time, Ar was used as a sputtering gas, the input power was 100 W, the size of the target was 4 inches in diameter, and the distance between the substrate and the target was 9
0 mm. Further, while maintaining the reduced pressure, the EL element substrate was transferred to another sputtering apparatus, and the sputtering was performed at a sputtering pressure of 0.3 Pa by a DC sputtering method using an Al target.
A protective electrode was formed to a thickness of 200 nm. At this time, Ar was used as a sputtering gas, the input power was 500 W, the size of the target was 4 inches in diameter, and the distance between the substrate and the target was 9
0 mm.

Lastly, a glass sealing plate is attached, and organic E
L display.

As a comparative sample, a sample in which the interlayer insulating layer was not blackened was manufactured.

Each of the obtained organic EL displays was continuously driven at a constant current density of 10 mA / cm ² by applying a DC voltage in the air. The contrast ratio between non-light emission and light emission when the entire screen was observed was 1: 100 in the comparative example, whereas the sample of the present invention was improved to 1: 500.

Also, FeO, Si, α
An equivalent result could be obtained when an interlayer insulating layer was formed by -C and blackened.

<Example 2> In Example 1, an interlayer insulating layer was formed without adding carbon black. In order to form the base of the element isolation structure, 2 μm of polyimide is placed on the substrate on which the ITO transparent electrode and the interlayer insulating layer are formed.
To a thickness of For polyimide, select a non-photosensitive material and make NMP (N-methyl pyrrolidone) to a concentration of about 5%.
And carbon black (primary particle size: 100
nm) was added, and the mixture that had been well stirred and mixed was applied by a spin coating method, and further applied at 150 ° C. for 30 minutes, followed by 3 minutes.
Bake at 00 ° C for 1 hour. Subsequently, a positive resist layer serving as an overhang portion is applied to a thickness of 3 μm, exposed,
Development was performed to obtain an element isolation structure. Otherwise, an organic EL display was manufactured in the same manner as in Example 1.

As a comparative sample, a sample in which the base of the element isolation structure was not blackened was manufactured.

Each of the obtained organic EL displays was continuously driven at a constant current density of 10 mA / cm ² by applying a DC voltage in the atmosphere. The contrast ratio between the non-emission state and the light emission state when observed over the entire screen was 1: 100 in the comparative example, whereas the sample of the present invention was improved to 1: 400.

<Example 3> In Example 2, in order to form the base of the element isolation structure, an FeO film serving as a base was formed on a substrate on which an ITO transparent electrode and an interlayer insulating layer were formed by 2 μm.
m was formed. RF sputtering was used as the sputtering conditions, the target was FeO, the distance between the target and the substrate was 80 mm, the input power was 500 W, the pressure during film formation was 0.3 Pa, and argon was used as a sputtering gas at a flow rate of 50 SCCM. Was.

Next, a positive resist layer serving as an overhang portion was applied to a thickness of 3 μm, exposed, developed, and etched to obtain an element isolation structure. Otherwise, an organic EL display was manufactured in the same manner as in Example 1.

When each of the obtained organic EL displays was evaluated in the same manner as in Example 2, almost the same evaluation was obtained. A similar evaluation was obtained when the material of the base was changed from FeO to Si (target: Si, the Si layer after film formation was in an amorphous state).

Example 4 In Example 2, in order to form the base of the element isolation structure, an α-C film serving as a base was formed on a substrate on which an ITO transparent electrode and an interlayer insulating layer were formed by 2 μm.
m was formed and patterned. The sputtering conditions were DC sputtering, the target was graphite, the distance between the target and the substrate was 80 mm, and the power input was:
The film formation was performed at 500 W, a pressure of 0.3 Pa during film formation, and argon as a sputtering gas at a film formation rate of 10 nm / min.

Next, a positive resist layer serving as an overhang portion was applied to a thickness of 3 μm, exposed, developed, and etched to obtain an element isolation structure. Otherwise, an organic EL display was manufactured in the same manner as in Example 1.

When each of the obtained organic EL displays was evaluated in the same manner as in Example 2, almost the same evaluation was obtained.

[0104]

As described above, according to the present invention, an object is to provide an organic EL device having improved contrast ratio and visibility. Another object of the present invention is to provide an organic EL device capable of realizing low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view conceptually showing a configuration example of an organic EL device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 hole injection electrode 3 interlayer insulating layer 4 organic layer 5 electron injection electrode 7 element isolation structure 7a overhang portion 7b base

Claims (3)

[Claims] 1. An interlayer insulating layer and / or an element isolation structure having a hole injection electrode, an electron injection electrode, and at least one organic layer between these electrodes, and formed around the hole injection electrode. An organic EL device with a black base. 2. The organic EL device according to claim 1, wherein the base of the interlayer insulating layer and / or the element isolation structure contains ferrous oxide, silicon, or amorphous carbon. 3. The organic EL device according to claim 1, wherein the base of the interlayer insulating layer and / or the element isolation structure has polyimide and carbon.